Advanced treatment of biologically pretreated coking wastewater by intensified zero-valent iron process(IZVI) combined with anaerobic filter and biological aerated filter(AF/BAF)

Experiments were conducted to investigate the behavior of the sequential system of intensified zero-valent iron process(IZVI) and anaerobic filter and biological aerated filter(AF/BAF) reactors for advanced treatment of biologically pretreated coking wastewater. Particular attention was paid to the performance of the integrated system for the removal of chemical oxygen demand(COD), ammonia nitrogen(NH3-N) and total nitrogen(TN). The average removal efficiencies of COD, NH3-N and TN were 76.28%, 96.76% and 59.97%, with the average effluent mass concentrations of 56, 0.53 and 18.83 mg/L, respectively, reaching the first grade of the national discharge standard. Moreover, the results of gas chromatography/mass spectrum(GC/MS) and gel permeation chromatography(GPC) analysis demonstrated that the refractory organic compounds with high relative molecular mass were partly removed in IZVI process by the function of oxidation-reduction, flocculation and adsorption which could also enhance the biodegradability of the system effluent. The removal efficiencies of NH3-N and TN were achieved mainly in the subsequent AF/BAF reactors by nitrification and denitrification. Overall, the results obtained show that the application of IZVI in combination with AF/BAF is a promising technology for advanced treatment of biologically pretreated coking wastewater.

Timing Sequence Changes of Landscape Plants in Shanghai Area,China

Based on published reports and direct observation,the common resources of landscape plant species in the Shanghai area were identified and studied in terms of the landscape characteristics of timing sequence changes over a one year time period.The results showed that there were 199 common landscape plant species in Shanghai,distributed in 67 families and 129 genera.These plants were categorized by three ornamental characteristics:flowers,foliage and fruits.The species were thus further analyzed according to the time periods which these characteristics were present.The results showed that flower ornamental distributed throughout the year,particularly from April to June,and plant species with colorful foliage could be seen every month,and particularly in November and December.On the other hand,few plant species with fruit ornamentals were observed in Shanghai area.The diversity of landscape timing sequence changes of the 199 plant species under examination was then analyzed by using the Shannon-Weiner and Simpson index formulas.The results showed that the higher diversity was observed in January,February and from August to October,while the lowest diversity was recorded from March to July and during November and December.The diversity of landscape characteristics of these plants was ranked according to foliage,flowers and fruit.Using this method,one park and one plant community were selected to evaluate the advantages and disadvantages of their time-changing plant landscape,with the goal of assessing the validity of the chosen ranking method.These results in the present study would be helpful to evaluate the plant landscape in a specified space and further enrich the diversity of plant and landscape by a target-oriented way.